Hydroformylation of olefins with the aid of rhodium catalysts is generally known (see, e.g., The Journal of Organic Chemistry, Vol. 34, No. 2, pp. 327-330, and U.S. Pat. Nos. 3,859,359 and 3,917,661).
From the prior art it is also known that phosphorous- or arsenic-containing ligands have a considerable effect on the ratio of the amounts of normal aldehydes and branched-chain aldehydes. The article of Pruett and Smith in The Journal of Organic Chemistry, Vol. 34, No. 2, pp. 327-330 teaches that generally in the hydroformylation of oct-1-ene with tri-substituted phosphorus-containing ligands, an aliphatic substituent gives a lower percentage of straight-chain (or normal) aldehyde than an aromatic substituent. This is in conformity with the numerous experiments disclosed by Pruett and Smith in U.S. Pat. No. 3,917,661 and the .DELTA.HNP value-theory in Table A. In the U.S. Pat. No. 3,917,661 is likewise disclosed as a suitable ligand, tri(p-chlorophenyl)phosphite, giving a high percentage of normal aldehydes from .alpha.-olefins. Other examples of ligands are tri-m-fluorophenyl phosphite are tri-m-trifluoromethylphenyl phosphite, as mentioned in U.S. Pat. No. 3,859,359; however, no details on the amount of normal aldehydes are given. But special attention is given for a preferred hydroformylation process, using phenyl group-containing phosphites as ligands (see column 8, lines 34-47).
Applicant has now found a specific group of fluorine containing organic phosphites and arsenites as ligands which give even higher percentage of normal aldehydes from .alpha.-olefins, but surprisingly also from .beta.- and other internal olefins.